Thickening agent for liquid hydrocarbons



Patented June 11, 1957 THICKENING AGENT FOR LIQUID HYDROCONS Robert D. Aylesworth, Sprinigdale, and Lou A. Stagemeyer, Cincinnati, Ohio, assignors to Emery Industries, lnc., Cincinnati, Ohio, a corporation of Ohio No Drawing. Application Gctober 23, 1952, Serial No. 316,564

3 Claims. (Cl. 44--7) This invention relates to the improvement in the thickening agents used to increase the viscosity of liquid hydrocarbons.

Soap-gelled gasoline is an important weapon of war, being the incendiary fuel used in flame throwers and in incendiary bombs. The gelled gasoline is known as napalm and the term, napalm thickener, is applied to the gelling agent. War surplus stocks of napalm thickener found post-war use to form gels used as the shock wave transmission medium for increasing the flow of oil from oil wells. In this process, known as the Hydrafrac process, a cheaper and less volatile fluid than gasoline is preferable.

The accepted composition of napalm thickener has been established for some time as the basic aluminum soaps of a blend of 50% coconut oil fatty acids, 2 oleic acid and 25% naphthenic acid (U. S. P. 2,390,609). Aluminum soaps of additional blends of these fatty and naphthenic acids have more recently been recognized as producing satisfactory gasoline gels. Such blends are as follows:

The basic aluminum soaps of the blends of fatty and naphthenic acid are prepared by the double decomposition procedure, i. e., by addition of an aqueous solution of aluminum sulfate to a dilute aqueous solution of the sodium soaps of the blended acids. The precipitated aluminum soaps are washed, dried and pulverized to form napalm thickener.

An effective gelling agent should satisfy the following requirements:

1. Remain stable in storage in finely divided granular form.

2. Disperse readily in liquid hydrocarbon to form a gel in reasonable time.

3. Form gel of suitable consistency and stability.

4. Contain ingredients which are readily available in quantity and which are of uniform quality.

In the development of soap-gelling agents for liquid fuels, it has been found necessary to use the fatty acidnaphthenic acid blends now in use because of deficiencies encountered in attempting to use the more common fatty acids (stearic, palmitic, oleic) and their blends.

Stearic acid had been found unsatisfactory since aluminum stearate required heat treatment to incorporate into the fuel and formed hard, friable gels instead of the desired cohesive and adhesive type gels. Aluminum soaps of lower chain length saturated fatty acids, although more easily incorporated into the fuel, gave gels which were too soft and unstable.

Oleic; acid was unsatisfactory since gelation with aluminum oleate couldnot be accomplished in a simple manner without heating, and excessive amounts of the soap were required to produce desired viscosity.

It is the purpose of this invention to provide an improved composition for the preparation of gellied hydrocarbon which requires less' gelling agent.

It is also the purpose of this invention to provide a gelling agent which dissolves readily and produces stable gels with the use of a minimum quantity of gelling agent.

It is the further purpose of this invention to provide a gelling agent which requires only the types of fatty acids which are readily available from domestic fats.

We have found that the adding of small quantities of the fatty dibasic acids obtained by the polymerization of unsaturated fatty acids to the mixtures of acids used in producing aluminum soap thickening agents achieves the purposes enumerated.

We have found that the use of from 1% to 20% of fatty dibasic acids alone with the fatty acids normally employed permits a decrease of from 10% to as high as 50% in the amount of aluminum soap gelling agent re quired to produce a gasoline jelly of a given consistency as compared to the gell obtained without the use of fatty dibasic acids. The lower percentages of fatty dibasic acids per unit employed, show the greatest elfect in increasing gel consistencies with the efiect gradually diminishing so that the increase from 15% to 20% is only moderate.

We have also found that when fatty dibasic acids are incorporated in the fatty acid composition, it is not necessary to use naphthenic or coconut acids. The elimination of coconut acids and naphthenic acids is desirable not only because they are generally more expensive than oleic or animal fatty acids but also because cocoanut acids are imported and may not be available in time of war, while the supply of naphthenic acids is limit-ed and finds numerous other war-time uses.

We have found that gasoline gels produced with fatty dibasic acids show less tendency to deteriorate on aging than the compositions used heretofore.

The fatty dibasic acids may also be used to control the rate of solution of the aluminum soaps in hydrocarbons. Small quantities generally increase the rate of solution while larger quantities in excess of the amount required to obtain maximum gelation may be employed if for any reason it is desired to reduce solution rate.

One method of preparing the fatty dibasic acids employed in our invention is by heating fatty acids containing appreciable percentages of polyunsaturated, aliphatic acids of 18-22 carbon chain length to high temperatures in the presence of a small amount of water to prevent decarboxylation, as described in U. S. Patent 2,482,761. Any other method of effecting a condensation of two molecules of a higher fatty acid may be employed; for example, the polymerization of the methyl or glyceryl esters followed by decomposition of the ester to produce the free acids. The dibasic acids may be separated from the monobasic acids and used in preparing gelling compositions or the unseparated mixture of dibasic and monobasic acids may also be employed as the monobasic acids and may constitute part of the monobasic acids of the compositions.

We have found that from 2% to 20% of fatty dibasic acids are effective in increasing gel strength, decreasing solution time and increasing stability of the gels.

The fatty dibasic acids are soluble in monobasic acid and are used either in solution or merely admixed with the monobasic acids prior to preparing the aluminum soaps. The aluminum soaps may be prepared according to the following typical procedure which was also used in preparing the aluminum soaps used in the examples.

3 EXAMPLES The aluminum soaps were prepared with the following molal ratios: 4.0 soap-forming acids, 6.2 caustic soda, 1.05 aluminum sulfate (A12(SO4)3.18H2O). This ratio is not fixed, however, and may be varied somewhat.

To prepare the aluminum soaps, a dilute soda soap solution is first prepared by adding the soap-formingacids to a'hot (80 C.) solution of the caustic soda, while agitating. The amount of water used is such as to give a soap concentration of about 5% to After formation of the soda soap solution, agitation is continued and the temperature maintained at about 80 C. while slowly adding the aluminum sulfate in the form of a solution of commercial aluminum sulfate (Alz(SO4)3). 18H2O. The precipitated aluminum soaps are separated by filtration and, after thorough washing, are dried at about 60 C. The dried aluminum soaps are pulverized to pass through a 6-mesh screen and be mostly retained on a -mesh screen.

For purposes of testing, the incorporation of the soap into the hydrocarbon liquid is suitably accomplished by first weighing the required amount of soap into a glass jar and then adding the required amount of liquid. The jar is immediately closed and the mixture shaken. The time required for thickening or gelling is noted and the thickened liquid then allowed to stand. Viscosities are determined for various periods of aging by suitable means.

The following examples more fully illustrate our invention:

Example 1 The aluminum soap of oleic acid containing 2%. of fatty dibasic acid was prepared and 5% dissolved in ordinary motor gasoline as previously described.

The aluminum soaps dissolved in one minute, produc- 5 A blend of fatty acids consisting'of--- Parts oleic acid 50 Distilled animal fatty acids Fatty dibasic acid 5 was converted to the aluminum soaps and dissolved in gasoline. The solution required 4 /2 minutes and after one day the jellied gasoline had a viscosity of 270 poises and after seven days, 104 poises.

A fatty acid blend of oleic acid and 50% distilled animal fatty acids but without the addition of fatty dibasic acids failed to dissolve to form a gel.

4 Example The aluminum soaps of a blend of fatty and naphthenic acids consisting of-- 30 parts cocoanut fatty acids 5 parts naphthenic acids parts of a composition consisting of:

47.5% distilled animal fatty acids 47.5% oleic acid 5.0% fatty dibasic acids were dissolved in gasoline. At 5% concentration solution was practically immediate. After twenty-four hours standing, the viscosity of the gel was 620 poises and after one week, the same reading was obtained.

In an identical test, 65 parts of oleic acid soap without fatty dibasic acids were substituted for the 65 parts of the composition listed above. At 5% concentration solution required /2 minute; the gel was also slightly cloudy but the viscosity of the gel was only 84 poises after 24 hours standing and had dropped to 54 poises after standing for one week.

Having described our invention, we claim:

l. A gasoline jelly comprising gasoline and substantially 2-15 thickening agent comprising -98% aluminum'soaps of oleic acid and substantially 2-20% aluminum soaps of dibasic acids which are condensation products of two molecules of unsaturated fatty acids of 18-22 carbons chain length.

2. A gasoline jelly comprising gasoline and substantially 2-l5% thickening agent comprising 80-98% aluminum soaps of monobasic acids of the group consisting of oleic acid, animal fatty acids, coconut oil fatty acids and naphthenic acids, and substantially 2-20% aluminum soap of dibasic acids which are condensation products of two molecules of unsaturated fatty acids of 1 8-22 carbons chain length. A v

3. A liquid hydrocarbon jelly comprising a liquid hydrocarbon and substantially 2-15% thickening agent comprising 8098% aluminum soaps of monobasic acids of the group consisting of oleic acid, animal fatty acids, coconut oil fatty acids and'naphthenic acids, and substantially 2-20% aluminum soap of dibasic acids which are condensation products of two molecules of unsaturated fatty acids of 18-22 carbons chain length.

References Cited in the file of this patent UNITED STATES PATENTS Mysels Dec. 27, 1949 Dean Dec. 2, 1952 OTHER REFERENCES 

1. A GASOLINE JELLY COMPRISING GASOLINE AND SUBSTANTIALLY 2-15% THICKENING AGENT COMPRISING 80-98% ALUMINUM SOAPS OF OLEIC ACID AND SUBSTANTIALLY 2-20% ALUMINUM SOAPS OF DIBASIC ACID WHICH ARE CONDENSATION PRODUCTS OF TWO MOLECULES OF UNSATURATED FATTY ACIDS OF 18-22 CARBONS CHAIN LENGTH. 